HP-8 Hydronic Expansion Tank

8-Liter (2.0 Gallon) Tank for Hydronic Heating & Cooling Systems| Aquasky HYDRO-PLUS Series | Made in Taiwan

HP-8 is an 8-liter (2.0 gallon) expansion tank specifically engineered for closed-loop hydronic heating and cooling systems. It effectively absorbs expanded fluid volume to control pressure build-up, ensuring the safety and stability of residential or commercial setups.

Built for high-performance environments, the tank supports a maximum operating pressure of 10 bar (150 psi) and temperatures up to 130°C (266°F). It is factory pre-charged to 1 bar (15 psi) and is fully compatible with propylene glycol mixtures of up to 50%.

With a diameter of 20.3 cm and a height of 29.75 cm, this compact tank offers a highly reliable solution. It is designed for convenient installation alongside non-potable water systems, delivering dependable performance in a space-saving footprint.

HP-8

Product Overview

The HP-8 is an 8-liter (2.0 gallon) hydronic expansion tank engineered specifically for closed-loop hydronic heating and cooling systems. As the fluid in your climate-control system changes temperature, it expands and contracts; the HP-8 safely absorbs this expanded fluid volume, effectively controlling the excessive pressure generated inside the system and preventing potential hazards.


Built with a robust sheet steel tank, the HP-8 utilizes a specialized, high-temperature-resistant EPDM rubber diaphragm to ensure exceptionally safe and reliable operation. To guarantee supreme durability, every single Hydro-Plus model is subjected to rigorous hydraulic testing at a pressure 1.5 times higher than the design pressure.


Manufactured with premium materials, welded according to strict ASME & EN procedures by certified welders, and compliant with IAPMO and EN standards, Aquasky HYDRO-PLUS tanks are the ultimate safety choice for your hydronic heating system, delivering a long service life and dependable performance.

Certification

Specifications and Technical Data

Parameter Value
Model Number HP-8
Total Tank Volume 8 liters / 2.0 gallons
Diameter 20.3 cm / 8.0 inches
Height 29.75 cm / 11.7 inches
Net Weight (NW) 1.9 kg / 4.2 lbs 
Gross Weight (GW) 2.3 kg / 5.1 lbs 
Shipping Volume 0.50 CUF 
Max. Operating Temperature 130°C / 266°F
Factory Pre-charge 1 bar | 15 psi
Max. Operating Pressure 10 bar | 150 psi
Connection 1/2" Cacbon Steel / Stainless Steel
Diaphragm Material High-temperature resistance EPDM Rubber
Tank Body Shell Cold Rolled Carbon Steel
External Coating Gray Paint
Air Nozzle Protection Brass cap with internal O-ring
Pre-charge Gas 100% Nitrogen

Key Features & Design Advantages

  • High-temperature resistant EPDM diaphragm for frequent heating/cooling cycles.
  • Durable cold-rolled carbon steel shell, welded to ASME & EN standards by certified welders.
  • 1.5x hydraulic pressure tested for safety and leak prevention.
  • Brass cap with internal O-ring ensures zero air loss from the air-vent.
  • Compatible with up to 50% propylene glycol, versatile for anti-freeze and commercial chillers.
  • Protective gray paint for professional appearance and environmental resistance.
  • 100% made in Taiwan.
Materials & Design Advantages

How the HYDRO-PLUS Pressure Tank Works

In closed hydronic heating and cooling systems, fluid volume changes drastically as the temperature rises and falls. The HP-8 safely absorbs this expanded fluid using a sealed, compressible air cushion space. It stores the fluid securely against the high-temperature EPDM rubber diaphragm, while the air chamber compresses to accommodate the volume change. This mechanism seamlessly controls excessive pressure, protects valves and piping, and maintains safe system parameters without venting fluid.

Key benefits

  • Absorbs excess fluid volume during thermal cycles.    
  • Protects system components (boilers, piping, valves) from damaging high pressure. 
  • Delivers a safe and stable system for residential and commercial hydronic applications. 
  • Guarantees peace of mind through strict manufacturing standards and a 1.5x design pressure hydraulic test.

Typical Applications 

  • Closed-loop residential and commercial hydronic heating systems.  
  • Hydronic cooling installations. 
  • Non-potable water applications (compatible with up to 50% propylene glycol mixtures).

Frequently Asked Question (FAQ)

Q1 : Will the HP-8 work for a standard home hydronic heater?

A: Yes, the HP-8 offers a 2.0-gallon capacity, making it a great fit for absorbing expanded fluid in standard residential setups.

Q2 : Does the tank come ready to install, or do I need to pump air into it first?

A: It comes ready to go with a factory pre-charge of 1 Bar (15 PSI), so it can often be installed right out of the box.

Q3 : Does the hot heating fluid touch the metal inside the tank?

A :  No, the internal fluid is safely contained by a high-temperature resistance EPDM rubber diaphragm.

Downloads & Certification Links

Hydronic Expansion Tank DM
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